Oxygenator

ABSTRACT

An improvement in a unitary blood oxygenator of the type having an oxygenating chamber, a settling chamber and a heat exchange chamber in communication with each other characterized by ribs formed in the oxygenating chamber for positioning the debubbling sleeve spaced from the walls of the chamber; further characterized by the provision of a settling chamber of reduced volume, preferably being thin in horizontal cross section and further characterized by refinements in the heat exchange jacket about the heat exchange chamber in the form of angularly oriented, indented ribs in the shell of the heat exchange chamber.

United States Patent Inventors Donald J. Bentley c/o BentleyLaboratories 3107 S. Kilson St., Santa Ana, Calif. 92707; Richard A. DeWall, 247 Northview Road, Dayton, Ohio 45419 Appl. No. 857,044 FiledSept. 11, 1969 Division of Ser. No. 601,000, Dec. 17 1966, Pat. No.3,488,158 Patented Oct. 26, 1971 OXYGENATOR 17 Claims, 6 Drawing Figs.

U.S. Cl 23/2585, 128/400, 165/169 Int. Cl A6lm 1/03 Field of Search23/2585;

128/400, D10. 3; 261/124, 153, DlG. 28; 165/169 [56] References CitedUNITED STATES PATENTS 2,981,253 4/1961 De Wall et al. 23/2585 3,103,9289/1963 Broman 23/258.5 3,256,883 6/1966 De Wall 23/2585 3,468,631 9/1969Raible et al 23/2585 Primary Exam iner-Joseph Scovronek AssistantExaminer-Barry S. Richman AttarneyHofgren, Wegner, Allen, Stellman &McCord ABSTRACT: An improvement in a unitary blood oxygenator of thetype having an oxygenating chamber, a settling chamber and a heatexchange chamber in communication with each other characterized by ribsformed in the oxygenating chamber for positioning the debubbling sleevespaced from the walls of the chamber; further characterized by theprovision ofa settling chamber of reduced volume, preferably being thinin horizontal cross section and further characterized by refinements inthe heat exchange jacket about the heat exchange chamber in the form ofangularly oriented, indented ribs in the shell of the heat exchangechamber.

PATENTEDnm 2s 18?! SHEET 16F 3 PATENTEDBBI 26 I97] SHEET 3 UF 3mmliillil OXYGENATOR REFERENCE TO RELATED APPLICATION This applicationis a division of our copending application Ser. No. 601,000 filed Dec.17, 1966, entitled Bubbler Assembly for Oxygenator" now U.S. Pat. No.3,488,158, issued .Ian. 6, 1970.

BACKGROUND OF THE INVENTION 1. Field of The Invention This inventionrelates to blood-treating apparatuses and, more particularly, to animprovement in a unitary blood oxygenator.

2. Brief Description of the Prior Art The present invention is animprovement in the blood oxygenators shown in the patent issued toDonald A. Raible et al., U.S. Pat. No. 3,468,631, issued Sept. 23, 1969,entitled Oxygenator with Heat Exchanger and further an improvement inthe structure shown in the patent to Richard A. DeWall, U.S. Pat. No.3,256,883, issued June 21, I966 and entitled oxygenator with HeatExchanger. Each of the structures disclosed therein is a complete bloodoxygenator assembly including an oxygenator chamber and a heat exchangechamber.

As stated with respect to the improvements set forth in each of theaforementioned application and issued patent, there is a continuing needand desire in the blood oxygenator art for thorough intermixing of bloodand oxygen and thorough debubbling of oxygenated blood and thoroughfiltering of particles from the blood, including the elimination ofaccumulated blood fragments. Most importantly, it is essential that suchfragments or bubbles are eliminated from the blood before. the blood isreturned to the patient, however, of course, it is necessary that theblood be provided with a proper amount of oxygen and heated to asufficient temperature prior to return to the patient. Thus, thestructure provided for treating the blood must be such as to provide forthe release of such bubbles, the filtering of such fragments and theprevention of any further bubbles and fragments in the blood. Thepresent invention is directed to meeting the aforementioned continuingneed and desire to provide blood treatment apparatuses which minimize oreliminate the undesirable effects set forth herein above.

SUMMARY OF THE INVENTION The present invention is directed, in brief, tothe provision of an improved unitary blood oxygenator of the type havingan oxygenating chamber, a settling chamber and a heat exchange chamberin communication with each other.

The best mode currently contemplated by us for carrying out theinvention includes the provision of a one-piece plastic molded structurehaving a generally circular-cylindrical oxygenating chamber, asubstantially thin elongate settling chamber in communication with theoxygenating chamber, and a generally circular-cylindrical heat exchangechamber therebelow. The interior of the oxygenating chamber is providedwith inwardly directed ribs and detents for holding the defoamingelement about the bubbler assembly, spaced from the walls of theoxygenating chamber. The central settling chamber is defined by twogenerally parallel, closely spacedapart sidewalls to provide a chamberof reduced volume with the lower end of the chamber having taperingsidewalls so that in operative position, a small volume of blood willbring the minimum level of blood in the central chamber in the bottom ofthe oxygenator chamber to eliminate churning and dripping which mightcreate undesirable bubbles in the blood. In addition, the rib structureabout the heat exchange chamber is altered to provide acutely angledblood passageways so as to prevent the free flow of blood with bubblesdownwardly and about the heat exchange chamber and to eliminate thepossibility of bubble-containing blood running directly into thecollecting chamber near the outlet of the oxygenator for return to thepatient.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated in apreferred embodiment in the accompanying drawings in which:

FIG. 1 is a side elevational view of the oxygenator device of theinstant invention, the view showing; the oxygenator device tilted at aslightly greater angle toward the vertical than is the case when it isin ordinary use;

FIG. 2 is an end elevational view taken from the left of FIG. 11;

FIG. 3 is an end elevational view taken from the right of FIG. 1;

FIG. 4 is an enlarged fragmentary sectional view of the oxygenatingchamber and the enclosed bubbler assembly taken as indicated along line4-4 of FIG. 2;

FIG. 5 is a partial sectional view of the heat exchanger assembly takengenerally along line 5-5 of FIG. I; and

FIG. 6 is a sectional view taken as indicated on line 6-6 of FIG. I toshow the general structural arrangement of the ribs in the heat exchangechamber.

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetail a specific embodiment therefor, with the understanding that thepresent disclosure is to be considered as an exemplification of theprinciples of the invention and is not intended to limit the inventionto the embodiment illustrated.

BRIEF DESCRIPTION OF THE. PREFERRED EMBODIMENT FIGS. ll, 2, and 3 eachshow the preferred embodiment of the bubble-type oxygenator device ofthis invention. The oxygenator device shown includes an uppercylindrical chamber 20 (commonly called an oxygenating chamber), anarrow central chamber 21 and a lower cylindrical chamber 22 (commonlycalled a heat exchanging chamber), and a collecting chamber 23. In use,the oxygenator device may be Suspended by hooks or other appropriatemeans passing through apertures 24 formed at opposite ends of the upperchamber 20. When in normal operation, the angle formed by the axis ofthe upper cylindrical chamber 20 with the horizontal is preferably inthe range of approximately 35 to 50. The structure shown in FIG. II isat a slightly greater angle and is not intended to il lustrate thepreferred angular relationship.

The chambers 20, 21, 22, and 23 are preferably formed from apolycarbonate plastic (sold by General Electric under the trademarkLexan) which may either be vacuum formed or injection molded to shapetwo self-sustaining substantially rigid shells 25, 26, which aresubstantially identical with each other except one is the mirror imageof the other. The two shells are each provided with a coplanarperipheral flange 27, and the peripheral flanges of the two shells areadhered together by a suitable adhesive to form a unitary, transparentstructure. The plastic is inert, nontoxic, impervious to the passage ofgases and liquids, and sterilizable. It contains no leechableplasticizers which may be traumatic to the blood, and it isexceptionally strong and durable to withstand accidental blows orshocks. In addition, it has a natural electrical surface charge which issimilar in nature to the natural charge of the hemoglobin of the bloodso that there is no tendency toward adherence between the blood and thesurface of the plastic.

The structure associated with the upper or oxygenating chamber 20 isbest shown in FIG. 4. This structure includes the bubbler assemblydesignated 28 of the instant invention, which bubbler assembly ispreferably mounted so that its longitudinal axis substantially coincideswith the longitudinal axis of the cylindrical chamber 20. The bubblerassembly shown herein is described in greater detail and claimed in ourcopending application Ser. No. 601,000, filed Dec. 12, I966, entitledBubbler Assembly for Oxygenator" now U.S. Pat. No. 3,488,158, issuedJan. 6, I970. Tire function generally of the bubbler assembly is tointermix oxygen gas with incoming venous blood so as to form films ofblood in bubble form,

lnum-r nun which blood bubbles are advanced in an oxygen atmospherethrough the bubbler assembly to an outlet or outlets. In other words, inthe bubbler assembly, oxygen is taken on by the venous blood and carbondioxide carried by such blood is released. The degree to which the bloodis saturated with oxygen at ambient temperatures and pressures dependsprimarily upon the extent to which all of the blood is bubbled, thecharacter of the films in the bubbles produced (that is their thicknessor thinness and size), and the time of exposure of the blood films tothe oxygen atmosphere.

As the blood bubbles pass out of the outlet of the bubbler assembly, thebubbles come into contact with a defoaming means 30. The defoaming means30 is preferably formed in the shape of a sleeve which is closed at oneend and fits over the outer lateral surface of the bubbler assembly 28.The sleeve is constructed of a plurality of similarly shaped sleevelayers of knitted mesh material which layers are nested one withinanother to provide a multitude of tortuous paths of flow. The knittedlayers 31 are preferably formed of polypropylene fibers each of which isgenerally smooth and round and presents no rough surfaces to the flow ofblood passing therethrough. Thus the layers have no rough edges whichmay cause damage to the hemoglobin. The polypropylene layers areimpregnated or coated with a nontoxic antifoam composition of themedical silicone antifoam type which is well known in the art, and whichwill not wash off in the blood during the debubbling operation. As theblood bubbles contact the defoaming layers, rivulets of oxygenated bloodare formed, and the free oxygen and carbon dioxide are given off andpass outwardly of the upper chamber.

As will be seen, oxygenated blood must pass through a considerableportion of the defoaming means and through a filter means in order toreach reservoir 21 and collecting chamber 23. As herein shown, the meshlayers 31 are retained in place about the bubbler assembly 28 by aporous cover or bag 32 preferably formed of nylon material and having apore size of about 0.125 sq. mm. which filters the blood as it passesout of the bubbler assembly. In the adult size oxygenator, the cover 32preferably has a surface area of approximately 144 sq. in. The nylon bag32 is provided with drawstrings 33 at one end which are drawn tightlyaround the bubbler assembly so that all of the blood flowing out of thebubbler assembly will be caused to pass through the nylon fabric. In theadult size bubbler oxygenator, it is preferred to provide seven layers31 of the polypropylene fabric, while in the pediatric and infant sizethe number of layers may be decreased. Between the two outermost layersof the polypropylene mesh material, a polyethylene sheet 34 ispositioned so as to extend about the bubbler assembly for nearly 360.The arcuately disposed lower marginal edge of the polyethylene sheet 34is normally positioned about 1% to 2 inches upwardly of the lower end ofthe oxygenator chamber 20, and the upper arcuate marginal edge of thesheet 34 is located approximately the same distance from the upper endof the oxygenator chamber 20. The purpose of the polyethylene sheet 34is to form a troughlike formation for the debubbled blood so that thisblood is caused to flow angularly downwardly through the mesh layers 31within the sheet 34 to maximize the debubbling operation. Also, as willlater be explained, the sheet 34 causes the blood to gradually flow tothe lower end of the oxygenator chamber so as to make a smootherentrance into blood in the central chamber 21. If the sheet 34 were notpresent, some of the debubbled blood may drip down and splash on bloodcollected in the central chamber 21 so as to cause undesirable bubbling.

The excess free oxygen from the bubbling operation and the oxygen andcarbon dioxide emitted in the debubbling or defoaming operation escapefrom the oxygenating chamber through vents 35. If desired, the capcontaining vents 35 may be spaced from the exhaust port to providedannular vents also. As best seen in FIGS. 1, 2, and 4, a number of pairsof arcuate indented ribs 36 are positioned to bear against the nylon bag32 and the layers 31 so as to space intermediate poraunn tions of thesemembers from the inner lateral surface of the oxygenator chamber 20,thereby preventing the outer surface of the nylon bag from bearingagainst the inner lateral surface of the oxygenator chamber 20 inpartially sealing relation. Thus gases are free to escape outwardlythrough the nylon bag, then upwardly to the top of the oxygenatorchamber 20, and finally longitudinally outwardly of the chamber 20between the inner spaced ends 36a of each of the pairs of ribs 36 (FIG.2) to the vents 35. The gases may also escape to the vents 35 frombetween the upper end of the nylon bag 32 and the inner face of theupper end of the oxygenator chamber 20, as shown in FIG. 4.

As best seen in FIG. 4, short indentations 42 are preferably formed atthe lower end of the chamber 20 to afford end supports for the nylon bag32 and thereby space the bag from the elongated, narrow, open upper end43 of the central chamber 21. Thus, the nylon bag 32 when wetted withblood will be prevented from lodging in sealing engagement with the openend or slot 43.

The narrow central or intermediate chamber 21 provides a kind ofreservoir for the oxygenated blood. The central chamber has sidewallportions 38a, 38b, which are generally parallel and rather closelyspaced. The sidewall portions 38a, 38b are joined to the large sidewallportions 40a, 40b by diverging sidewall portions 41a, 41b. The sidewallportions 40a and 40b are also generally parallel but, because of thediverging sidewall portions 41a and 41b, are spaced farther apart thanare the sidewall portions 38a and 38b. Thus the lower end of the centralchamber or reservoir 21 accommodates a small volume of oxygenated bloodand will fill rather rapidly in use so that during use the level of theblood will preferably extend into the lower end of the upper oxygenatorchamber 20 (see FIGS. 1 and 4) and inundate the lower marginal edge ofthe sheet 34.

The lower mating portions of shells 25, 26 afford the lower cylindricalchamber 22, and the shell portions are provided with indented pairs ofarcuate ribs 44, the corresponding pairs in each shell portion beingpositioned in a plane extending at an acute angle to the axis of thelower chamber 22, as shown in FIG. 1. The central chamber 21communicates with the cylindrical chamber 22 through a narrow elongatedslot 45 extending substantially the full length of the chamber 22. t

The lower chamber 22 houses a water jacket 46 which makes a close fitwith and abuts the arcuate ribs 44 so as to arcuately provide a numberof wide, shallow passages 49 for blood flow between the outer surface ofthe water jacket 46 and the inner surfaces of the shells 25, 26, thedepth of the passages preferably being on the order of 0.0065 to 0.0080inches.

The water jacket 46 is hermetically sealed at 47, and fittings 48 areprovided for connection to a source of temperature control liquid so asto control the temperature of the wide, thin streams of oxygenated bloodpassing over the outer surface of the water jacket. In the adult sizeoxygenator, the heatexchanging surface of the jacket 46 preferably hasan area of approximately 270 sq. in.

In addition to defining wide, shallow passages 49, the ribs 44 functionas a bubble trap for any gas which might on occasion come out ofsolution. Although the passages are inclined, the blood will tend toflow in a perpendicular direction which creates a minimal backwash alongthe lower margin of each rib 44 and affords an effective bubble trap. Atflow rates over 4 liters per minute, the pressure has been measured tobe about 1 cm. of water less next to the lower margin of each rib 44than in the center of a passage 49. This pressure differential tends todraw any bubbles upwardly out of the blood and against the lower marginof the rib; thereafter hydrostatic pressure causes the bubbles to riseupwardly to the surface of the blood in the central chamber 21 andthence upwardly and outwardly to the vents 35.

From the chamber 22 the temperature-controlled oxygenated blood passesout an elongated port 50 extending the length of the bottom of chamber21 into the collecting chamber 23. At one end the port 50 is narrowedsubstantially in width to a very small fraction of an inch as a resultof the parallel, closely adjacent fingerlike sections 51a, 51b formed inshells 2, 26, respectively. Thus, in operation of the device, the narrowend of port 50, which is positioned lower than the remainder of theport, will accommodate only a relatively small amount of blood flowingtherethrough; and therefore the blood does not flow preferentially onlyaround the lowermost part of jacket as, but also flows about upper partsof the jacket to make maximum use of the inclined heat-exchangingsurface of the jacket. A small passage is also preferably providedextending from the extreme bottom corner of the heat exchange chamber tothe collecting chamber to assure complete drainage of the heat exchangechamber. From the collecting chamber 23 the oxygenated blood isconducted through the discharge ports in the fittings 52a, 52b to thearterial system of the patient.

in operation, blood enters the oxygenating chamber 20 through bloodinlets 53 and oxygen is fed into the oxygenating chamber through inlet54. The blood and oxygen are intermixed and travel through the tortuouspassageway 55 in the interior of the bubbler 2b and, particularly,through upper segment 56, around connecting segment 57 into lowersegment 58 and finally into central segment 59 from which the blood isfed outwardly of the bubble through outlet 60. After passing throughoutlet 60, the blood passes outwardly and downwardly of the exterior ofthe bubbler 2% in contact with the defoaming means 30 whereupon sheet 3dcauses the blood to flow downwardly and outwardly through slot 43 intothe central chamber or reservoir, 21.

In central chamber 21, the blood is held in a generally sheetlike columnand flows therefrom by means of opening 45 into the heat exchangechamber 22 in a divided annular path around the water jacket 46. Theblood travels in the shallow passages 49 which are acutely angledrelative to the axis of the heat exchange chamber and the blood bubblestend to rise upwardly along ribs 44. From the heat exchange chamber, theblood travels to the blood-collecting chamber 23 from which it may bereturned to a patient through discharge ports in fittings 52a and 52b.

The foregoing detailed description has been given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom, as some modifications may be obvious to those skilled in theart.

We claim:

1. A blood oxygenator and heat exchanger comprising: a casing; anoxygenator chamber in the upper part of the casing with blood and oxygeninlet means and gas outlet means, the oxygenator chamber having a topand bottom edge and forward and rear ends, and means along the bottomedge of the oxygenator chamber defining an elongate trough extendingsubstantially from the front to rear end of the oxygenator chamber forfeeding blood downwardly therefrom; and a heat exchange chamber in thelower part of the casing in communication with the oxygenator chamber bymeans defining an opening at the top thereof, the heat exchange chamberincluding means for conducting a heat exchange medium toward and awayfrom the heat exchange chamber and a heat exchange element within thecasing in the heat exchange chamber, said heat exchange element havingan exterior defined by a shell, with rib means in the lower part of thecasing defining, together with the heat exchange element shell, aplurality of wide, shallow blood passages about the heat exchange element, said passages extending at an acute angle to the axis of the heatexchange chamber and being in communication with a blood outlet meansfor return to the arterial system of a patient.

2. The oxygenator of claim 11 wherein the rib means defining the shallowpassages are indented in the casing relative to the heat exchangechamber.

3. The oxygenator of claim 2 wherein the rib means generally abut theheat exchange element in the heat exchange chamber.

3. A blood oxygenator comprising: a casing; an oxygenator chamber in theupper part of the casing with blood and oxygen inlet means and gasoutlet means, the oxygenator chamber having a top and bottom edge andforward and rear ends, and means along the bottom edge of the oxygenatorchamber defining an elongate trough extending substantially from thefront to the rear end of the oxygenator chamber for feeding blooddownwardly therefrom; and a heat exchange chamber in the lower part ofthe casing with means for conducting a heat exchange medium toward andaway from the heat exchange chamber and means for conducting blood awaytherefrom; and a settling chamber between the oxygenator chamber and theheat exchange chamber defined by spaced walls in communication with saidoxygenator chamber through said elongate trough and in flowcommunication with said heat exchange chamber, said walls being closelyspaced apart relative to the width of said chambers to define asheetlike column in the space between the heat exchange and oxygenatorchambers of reduced thickness relative to the said chambers, one end ofthe settling chamber adjacent the heat exchange chamber being of furtherreduced thickness relative to the remainder of the settling chamber.

5. The oxygenator of claim d wherein the walls of the settling chamberare generally planar.

6. The oxygenator of claim d wherein the walls of the settling chamberextend from the edges of said opening downwardly towards said heatexchange chamber and are spaced apart a distance substantially nogreater than the distance between the opposite edges defining thesheetlike opening in the bottom of the oxygenator chamber.

7. The oxygenator of claim 6 wherein the heat exchange chamber has anopening therein, the edges of which define a generally thin, elongateslot with a reduction at one end, with the walls of the settling chambergenerally coinciding with the edges of the thin, elongate slot at thetop of the heat exchange chamber.

8. In a unitary blood oxygenator of the type having an oxygenatingchamber of a generally hollow interior cylindrical configuration with abubbler assembly and surrounding defoamer sleeve positioned therein, theimprovement which comprises: rib means extending inwardly from theinterior of the oxygenator chamber a distance sufiicient to hold abubbler assembly and surrounding defoamer sleeve intended for usetherein spaced from remaining portions of the oxygenator chamberinterior.

9. The oxygenator of claim 8 wherein the rib means are interrupted toprovide gas passageways therethrough.

10. The oxygenator of claim 9 wherein the rib means are formed in theupper part of the oxygenator chamber.

11. The oxygenator of claim 10 wherein the rib means are interrupted atthe top portion of the oxygenator chamber.

12. The oxygenator of claim 10 wherein the rib means lie in planesgenerally transverse to the axis of the oxygenator chamber.

13. The oxygenator of claim 12 wherein the rib means are discontinuousat the bottom of the chamber.

M. in a blood oxygenator of the type having an oxygenator chamber withmeans for conducting blood and oxygen thereto and gas outlet means andtrough means at the bottom thereof for feeding blood to other componentsof the oxygenator and a generally hollow interior cylindrical oxygenatorchamber with a debubbler assembly and surrounding defoamer sleevepositioned therein, the improvement which comprises: bubbler assemblysupporting detent means in the oxygenator chamber near the trough meansfor supporting portions of the bubbler assembly and surrounding defoamersleeve spaced away from said trough means.

115. The oxygenator of claim M- wherein the detent means are formed onthe forward end of the oxygenator chamber.

16. The oxygenator assembly of claim 15 wherein the detent means areformed on opposite sides of the through means.

17. The oxygenator of claim 16 wherein the detent means are formed inthe lower end of the oxygenator chamber.

2. The oxygenator of claim 1 wherein the rib means defining the shallowpassages are indented in the casing relative to the heat exchangechamber.
 3. The oxygenator of claim 2 wherein the rib means generallyabut the heat exchange element in the heat exchange chamber.
 4. A bloodoxygenator comprising: a casing; an oxygenator chamber in the upper partof the casing with blood and oxygen inlet means and gas outlet means,the oxygenator chamber having a top and bottom edge and forward and rearends, and means along the bottom edge of the oxygenator chamber definingan elongate trough extending substantially from the front to the rearend of the oxygenator chamber for feeding blood downwardly therefrom;and a heat exchange chamber in the lower part of the casing with meansfor conducting a heat exchange medium toward and away from the heatexchange chamber and means for conducting blood away therefrom; and asettling chamber between the oxygenator chamber and the heat exchangechamber defined by spaced walls in communication with said oxygenatorchamber through said elongate trough and in flow communication with saidheat exchange chamber, said walls being closely spaced apart relative tothe width of said chambers to define a sheetlike column in the spacebetween the heat exchange and oxygenator chambers of reduced thicknessrelative to the said chambers, one end of the settling chamber adjacentthe heat exchange chamber being of further reduced thickness relative tothe remainder of the settling chamber.
 5. The oxygenator of claim 4wherein the walls of the settling chamber are generally planar.
 6. Theoxygenator of claim 4 wherein the walls of the settling chamber extendfrom the edges of said opening downwardly towards said heat exchangechamber and are spaced apart a distance substantially no greater thanthe distance between the opposite edges defining the sheetlike openingin the bottom of the oxygenator chamber.
 7. The oxygenator of claim 6wherein the heat exchange chamber has an opening therein, the edges ofwhich define a generally thin, elongate slot with a reduction at oneend, with the walls of the settling chamber generally coinciding withthe edges of the thin, elongate slot at the top of the heat exchangechamber.
 8. In a unitary blood oxygenator of The type having anoxygenating chamber of a generally hollow interior cylindricalconfiguration with a bubbler assembly and surrounding defoamer sleevepositioned therein, the improvement which comprises: rib means extendinginwardly from the interior of the oxygenator chamber a distancesufficient to hold a bubbler assembly and surrounding defoamer sleeveintended for use therein spaced from remaining portions of theoxygenator chamber interior.
 9. The oxygenator of claim 8 wherein therib means are interrupted to provide gas passageways therethrough. 10.The oxygenator of claim 9 wherein the rib means are formed in the upperpart of the oxygenator chamber.
 11. The oxygenator of claim 10 whereinthe rib means are interrupted at the top portion of the oxygenatorchamber.
 12. The oxygenator of claim 10 wherein the rib means lie inplanes generally transverse to the axis of the oxygenator chamber. 13.The oxygenator of claim 12 wherein the rib means are discontinuous atthe bottom of the chamber.
 14. In a blood oxygenator of the type havingan oxygenator chamber with means for conducting blood and oxygen theretoand gas outlet means and trough means at the bottom thereof for feedingblood to other components of the oxygenator and a generally hollowinterior cylindrical oxygenator chamber with a debubbler assembly andsurrounding defoamer sleeve positioned therein, the improvement whichcomprises: bubbler assembly supporting detent means in the oxygenatorchamber near the trough means for supporting portions of the bubblerassembly and surrounding defoamer sleeve spaced away from said troughmeans.
 15. The oxygenator of claim 14 wherein the detent means areformed on the forward end of the oxygenator chamber.
 16. The oxygenatorassembly of claim 15 wherein the detent means are formed on oppositesides of the through means.
 17. The oxygenator of claim 16 wherein thedetent means are formed in the lower end of the oxygenator chamber.